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Without being chastised, I moved my posts from the BBMG/Strafer to here, I guess it's a better fit.
After being frustrated with my failed blow-forward design, I began looking to incredibly complicated designs, including Caselman and Feltman. Searching on Feltman, which was truly my inspiration for trying to build a BBMG (the little kid in me WANTS one!) I ran across some posts for JSRs ideas on mechanically operated BBMGs.
I built a crude prototype using the steel piston from my failed blowforward design, by cutting a notch in it, and drilling out a new piece of HDPE.
The prototype leaks air like hell, the jagged notch from the die grinder cut to the piston caused several jams, but IT WORKED!!!
I got a very satisfying POP-pa-POP-pa-POP-pa-POP-pa-POP-pa-POP-pa-POP-pa-POP (you get the idea)...the bbs left the receiver (no barrel yet) @150 psi so fast that I could not see them exiting.
I turned the rotor (for now) with my cordless drill.
I'm excited to continue to develop this, and I promise to post pics.
Next phase--one of my employees is cutting me some precision rotor valves on his lathe, and I will transfer from the HDPE to aluminum receiver.
Hopefully, with the Christmas holiday (we close our store between Christmas and New Years), I'll have time to turn this into the real deal!
(I don't have the link handy for JSRs design, but search this board for Feltman, and it's the only rotor concept JSR posted)
Truly, for those of you curious, with some time on your hands, ALL of JSRs mechanico-pneumatic designs are technically feasible--spend some time and try them out!
Ummm...is it wrong to quote yourself?
glad to hear you were successful even with your improvised setup
That's well posh, I wish I had underlings to make my BBMGs for me
For everyone's benefit, pics/video would be most welcome.
edit: I'm trying to reply to your mail but hotmail is being a female lady dog of the opposite sex.
At those pressures you can expect high velocities and impressive penetration, the damage videos would be tremendous
This effectively doubles the rate of fire for a given rotor speed meaning you don't have to spin it so fast, ie less stress on the system and overcoming friction is less important, so good idea all round, kudos.
Well, my "minion" came through with my rotor/valve today. he was even so kind as to tap the center for my shaft! Only cost me a box of 7mm bullets for his handloading!
Unfortunately, I have family obligations tonight and tomorrow night, so the best I might pull off tonight is some photos of the rotor.
I guess I don't get to play until Sunday!
Here's some poor cell-phone pics, I thought I could at least give a teaser while I'm still here at work--Last day of the year for me though! Woohoo!
edit #3--poor me, I keep editing my posts, so no-one knows there's something new here!
1.) Rather than the "notched" rotor that JSR initially envisioned, I went with the design as shown. I am afraid it might cause some feeding issues, but it will be much easier to seal well.
2.) If I do have feeding issues, I am thinking of creating a "ramp" (elongating the opening) toward the cylinder walls. This would keep a bb from riding on the edge of the rotor and rolling against the wall. (in theory)
3.) I'm curious if Delrin could be machined to a tighter seal and accomplish the same end-goal. I might have to play with that while I am on vacation next week.....
Before I get jumped all over for the double post, I edited my previous post 3 times, and I'm curious about the response to my questions posted above, #1, #2, #3...
I appreciate the response from the members here. I just want people to know this thread is alive!
Don't worry that's quite all right, bumping for that purpose is generally allowed.
I'm sure you'll get a lot of attention once you post the videos of it in action
The rotor design looks good, my one concern would be burst fire, I had envisioned when I first came up with the idea that when the notch would be in line with the barrel, it would be covered so only one BB at a time would come out. All you'd need is a pin really that would obstruct further flow of BBs when the notch is in the "firing" position, without blocking off the airflow.
With your design this isn't possible as more than one BB will gather in the rotor channels, so pending the revs per minute I'd say a double feed is definitely a potential issue.
DAMN YOU JSR!!!!!!!!
You cursed me!
Double feed is more than an issue, it jammed up and killed my pretty little aluminum rotor! It might be recoverable, but it won't seal near as well after polishing out the gouge.
Damn I need a lathe, I could keep prototyping without depending on others!
So....if I scrap this and go with a small rotor with a notch, how do I go about drilling a hole within a 1" chamber to place a pin over the firing position? My dentist likes me, but I don't think he'll loan me his right angle drill!!
Tis not often the words 'Success' and 'JSR' go together in the same sentance, but when they do...
Apologies, I should have mentioned the double feed issue sooner, but I figured you already had it covered. Ah well, you live, you learn.
Can't you just drill through the whole chamber then seal the pin in with epoxy, or just use a bolt?
Oi! The only reason i have so many failures is that I actually put my ideas to the test :p
Ha, how typical of you JSR to mention epoxy not everyone is a epoxy specialist I cant wait to see the final device in action, you must post good pics of thehole gun, and post some vids
~ AUSSIE LAND ~
Silly me to not have considered epoxy! Of course I should have expected that to be JSR's thought!
Right now the "whole gun" is just a 2"x2.5"x3" block of aluminum, for testing purposes.
Until I have an action that resembles consistent functionality, I don't want to waste a lot of time on "pretty"!
I am getting some good ideas for what the final gun will look like though, so we'll see how the testing goes.
To all, I'm taking a several day frustration break, so I haven't disappeared, I'm just going to spend a few days sheetrocking my woodshop instead of spending an ENTIRE day to find out another way that doesn't work!
Merry Christmas all!
Don't throw away your offcuts...
My wife, who tolerates my silly little projects keeps reminding me of how many different filaments that Edison tried before he created a working incandescent bulb.
I don't know if I'll live long enough to try all of JSR's ideas!
Got the shop about 50% sheetrocked...it's half of the second floor of my 30x60 barn--I tore down the old roof (gable) and replaced with a gambrel roof (I built every truss in place individually!) with the "flat" part of the ceiling at 11', so I'll have lots of room (30x30 give or take). It's just hard to deal with tools and stuff when it's 8 degrees outside and the barn isn't heated (yet)!
When I get this done, and get the woodstove installed, I'll get back on the BBMG projects.
I'm probably out for a few weeks while I tape and texture and move my tools into this space!
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